No-Repeat Group Mixer
Form groups while avoiding past pairings.
Built and maintained by Paul Clark, Redmoon Software · Last checked
Week after week the same people drift into the same clusters — this mixer breaks that up. Paste your roster, set people per group, and it generates up to 40 candidate groupings and keeps the one with the fewest repeated pairings from past sessions. Pairing history (the last 500 pairs) lives in your browser, so recurring classes, book clubs, and standup teams stay genuinely shuffled.
Enter. Paste your roster of names and set how many groups or members you want.
0 items
Click Mix groups to see a result.
Options
Recent results
- No history yet.
How it works
- Enter. Paste your roster of names and set how many groups or members you want.
- Mix. Click "Mix groups" to generate fresh groups that avoid recent pairings.
- Reuse. Come back next session and mix again; past pairings are remembered automatically.
- Reset. Use Reset history in Options to wipe past pairings and start fresh.
About the No-Repeat Group Mixer
Built to break up the same clusters
This is the tool for the class or team that always ends up in the same groups. It generates forty candidate arrangements, counts how many pairings in each are ones people have already been grouped with, and keeps the arrangement with the fewest repeats.
That is a stronger effort than a single shuffle, and it is still a heuristic rather than an optimal solution. Over enough rounds every pairing has occurred and the tool is choosing between arrangements that all repeat — at which point it quietly gives you the least-bad one rather than telling you it has run out of novelty.
Group size and the remainder
Set the group Size and the tool makes as many groups of that size as it can. When the number does not divide evenly, the last group is smaller — twenty people in groups of three gives six threes and one two.
A group of one is the case to watch for. Twenty-two people in groups of three ends with a single person on their own, which for most activities is worse than a group of four. If the arithmetic lands badly, changing the size by one usually fixes it.
The memory is per browser
The record of who has been grouped with whom is stored locally in this browser. A teacher using the same laptop all term accumulates a genuinely useful history; the same teacher on a different machine starts from nothing and the first mix will repeat pairs freely.
It also means the history is not shared between colleagues teaching the same class, and there is no way to see or edit what it has recorded — it is a black box that gets better the longer you use one device.
Frequently asked questions
How does it know who has already worked together?
After every mix, each pair of groupmates is saved to your browser's local storage. On the next mix the tool scores up to 40 random candidate groupings against that record and keeps the one with the fewest repeats.
What does "Repeats from history" mean under the results?
It counts how many pairs in the new grouping have been grouped together before. Zero means a completely fresh mix; the number naturally creeps up over many sessions as unused combinations run out.
What if my roster doesn't divide evenly into groups?
Groups are filled to your chosen size and whoever is left forms a final smaller group. With 16 people in groups of three, for example, you get five full groups plus one leftover person.
How do I start over with a clean slate?
Click Reset history in Options to wipe all stored pairings. New names added to the roster need no reset — they have no history yet, so the mixer places them freely.
Does pairing history follow me to another device?
No. History is stored per browser on the device you used, and nothing is uploaded. Mixing the same roster on a different computer starts from an empty record, so run recurring sessions from one machine.
Related randomizers
Further reading
- Mixing groups so people aren't stuck with last week's partners
Random groups feel fresh the first time and stale by the third, because the same pairs keep landing together. Here's how a mixer that remembers past pairings keeps breaking people up week after week.
- Running a multi-round debate tournament without repeat matchups
One debate round is easy to randomize. A tournament of four or five rounds needs a plan so nobody argues the same side twice in a row or faces the same opponent all afternoon. Here's how to sequence rounds with the debate pairer.
- Picking a group-size range for the activity, not the headcount
Most people set a group-size range by dividing their headcount and guessing. Here's how to pick min and max based on what the activity actually needs — with real ranges for book clubs, hackathons, classroom stations, and party games.
- Splitting a list into groups that don't all have to match
Not every activity needs equal-sized teams — sometimes you want groups of three here, five there, and no awkward leftover pair. Here's how a variable-size group splitter handles the range instead of forcing one fixed number.
- Pair everyone up without landing the same partners again
Partner work falls apart when the same two people keep getting matched. Here's how a random pair generator splits a group into twos, handles the odd person out, and remembers past pairings so this week's partners are new.
- Split a video call into breakout rooms in one click
Manually dragging twenty names into Zoom breakout rooms is the slowest part of any workshop. Here's how a breakout room assigner splits the roster instantly, keeps the pairs you need together, and stops the same people clustering every round.
- A random seating chart that actually mixes people up
Friends cluster, strangers hover by the door, and the same three people end up together every time. Here's how a random seating chart breaks up the cliques fairly — and the one table-size detail that decides whether anyone sits alone.
- Random debate pairings (and which side you argue) without the bias
Letting students pick their own debate partners and the side they already believe defeats the whole point of debate. Here's why randomizing both the pairing and the pro/con assignment builds better arguers — and how a debate pairer does it fairly.
- Cold-calling without the dread: fair student picking that actually works
Random student selectors only help if students believe they're fair — and if the teacher uses them thoughtfully. Here's how to call on students randomly without raising anxiety, plus how to handle groups, seating, and turns.